Our overall goals are to increase fundamental knowledge of factors that govern PNS and CNS nerve fiber growth and maintenance, as well as survival of the parent neuronal cell body, and to better understand mechanisms involved in the development of connections and adaptation and behavioral plasticity in different areas of the CNS. The individual projects seek to investigate: a) nonneuronal cell secretory products (both soluble and insoluble) that promote CNS neurite growth and neuronal survival in the animal and in culture, b) regenerative potential of cultured CNS growth cones under differing environmental conditions to better understand differences in growth capacity, c) distribution and molecular associations of myosin, actin and several actin-associated proteins in cultured growth cones to clarify mechanisms responsible for oriented growth of neuronal processes, d) improving functional recovery following nerve repair by ameliorating the response of sensory neurons to injury with the administration of nerve growth factor, e) the role of synaptic transmitters in visual cortex development, f) physiological and morphological substrata for the process of adaptation of the vestibulo-ocular reflex, g) response properties and connections of surviving somatic sensory cortex receiving cortical lesions in infants vs. adults to search for the basis of observed behavioral recovery in the infant, and h) cerebellar unit and spindle afferent firing, reflex EMG changes and stiffness and damping of the monkey's wrist during prevention of oscillations produced by novel loads through adaptive (plastic) control of movement behavior. The investigators have expertise in diverse experimental paradigms and techniques, yet share strong common interests in pursuing study of mechanisms of neurite growth and analyzing ways in which to best investigate adaptive behavior. Funding is requested to support in a cost-effective way shared facilities (computer expertise, electron microscopy and animal support) and to foster interaction and collaboration among the participants to facilitate progress toward the goal of better understanding basic mechanisms of regeneration and useful plasticity.